1. Field of the Invention
The present invention generally relates to a method for patrol inspecting and locating a radioactive substance and a device for carrying out the method.
2. Description of the Related Art
In an application for such as environmental protection or security, when a radioactive substance is monitored and administrated, it typically needs to measure radioactive distribution within a certain region or to seek a lost radioactive source. A movable patrol spectrometer is a device for detecting the radioactive substance with a positioning system thereon, which may be mounted on a motor vehicle, a helicopter, a ship or other carriers. The positioning system may acquire current geographic positions and gamma spectrometry or neutron count rate of the radioactive substance in real time. The movable patrol spectrometer comprises GPS positioning system besides components typically comprised in a conventional spectrometer, for example, a detector, a power supply, a preamplifier, an electronic module, a MCA (Multichannel Analyzer) and data processing unit. In addition, the movable patrol spectrometer focuses on acquiring, saving, reading and analysis of numerous sampled data in a high efficiency. By means of the conventional movable spectrometer, the radioactive level in a travel route may be measured, but the radioactive distribution in the local region in which the route is located may not be attained. For example, when a vehicle-mounted patrol spectrometer carries out inspection along a road, it can only mark out the radioactive levels at respective points on the road, but it fails to get specific conditions of the radioactive distribution within a certain range on both sides of the road. If it is used to seek a lost radioactive source, then it is impossible to determine the specific position of the radioactive source.
Some special devices for determining the position of the radioactive source are also proposed. One class of them carry out locating by imaging, for example by a gamma camera. Another class of them have collimators and rotating units. By means of the collimators, a direction in which radioactive source is located may be determined and the position of the radioactive source may be determined by measurements of a plurality of positions. However, as all of these devices need to measure fixed points for a long time and have a low detection efficiency, they are not suitable to the patrol inspection. They may only be used to carry out further measurements after the patrol spectrometer has determined suspicious regions.
In view of this, there indeed is a need to provide a patrol inspection device and a patrol inspection method for rapidly and efficiently measuring radioactive intensity distribution in a detection region around the patrol inspection route and determining the positions of the radioactive substances.